The present invention relates to a device for checking the position of various points of a vehicle, the term vehicle being taken in a broad sense and covering both automotive vehicles and other types of vehicles such as boats, motorcycles, aircraft or parts thereof.
In order to ensure the safety of road users, it would be advantageous to make systematic tests of the vehicles, by periodically inspecting the symmetry of the vehicle with respect to its longitudinal axis as well as the proper position of a certain number of characteristic points.
It is nowadays only after a vehicle has been in a serious accident that an exact check thereof is made, by "putting it through on the surface plate."
When an automotive vehicle has been in an accident, it is desirable to make a controlled alignment of the deformed parts, so that they will be brought back to their original positions. To this effect, one conventionally uses a surface plate comprising a rectangular chassis of metal on which the vehicle is mounted by means of four jaws which clamp the underbody. The longitudinal, lateral and vertical dimensions of the four jaws is a function of the type of vehicle to be repaired. After the vehicle has been correctly positioned and fixed on the surface plate, a measuring frame with longitudinal graduations is positioned on the surface plate and under the vehicle. After the frame has been positioned relative to the vehicle with respect to three adjustment points serving as references, taken in an undeformed part of the vehicle, the chassis is blocked on the surface plate. On the measuring frame, graduated rulers are intended to be fixed transversely, on which can slide vertically adjustable cursors carrying measuring fingers or posts ("towers") whose height position is marked by a graduated index.
For each type of vehicle the repairman has available the three dimensions of a certain number of characteristic points, as well as accessory ones intended for measuring each point. The various values are read, respectively, on the longitudinal rulers, on the transverse rulers, and on the posts.
This procedure is not entirely satisfactory, for a number of reasons. First of all, it necessitates purely manual measuring, sometimes done in zones difficult to reach, which may cause errors. Also, in view of the deformations of the vehicle and the presence of the means for securing, aligning and checking it, it is not possible to get to all points of the body and of the chassis. Then, it is necessary to calculate, from the reference coordinates, the coordinates of the points identified on the technical data sheet, which is lengthy and tedious and may be another source of error. Also, the operator must compare the values of the measurement performed to the values of the measured point appearing on the reference sheet.